diff --git a/packages/contact-importer/src/importer.js b/packages/contact-importer/src/importer.js
index a03d78c54..19d2ae2f3 100644
--- a/packages/contact-importer/src/importer.js
+++ b/packages/contact-importer/src/importer.js
@@ -2,15 +2,14 @@
 'use strict';
 
 const Bottleneck = require('bottleneck');
-const EventEmitter = require('events').EventEmitter;
+const { EventEmitter } = require('events');
 const chunk = require('lodash.chunk');
 const debug = require('debug')('sendgrid');
 const util = require('util');
 const queue = require('async.queue');
 const ensureAsync = require('async.ensureasync');
 
-const ContactImporter = module.exports = function(sg, options) {
-  options = options || {};
+const ContactImporter = module.exports = function(sg, options = {}) {
   const self = this;
   this.sg = sg;
   this.pendingItems = [];
@@ -32,26 +31,24 @@ const ContactImporter = module.exports = function(sg, options) {
   this.queue = queue(ensureAsync(this._worker));
 
   // When the last batch is removed from the queue, add any incomplete batches.
-  this.queue.empty = function() {
-    if (self.pendingItems.length) {
-      debug('adding %s items from deferrd queue for processing', self.pendingItems.length);
-      const batch = self.pendingItems.splice(0);
-      self.queue.push({
+  this.queue.empty = () => {
+    if (this.pendingItems.length) {
+      debug('adding %s items from deferrd queue for processing', this.pendingItems.length);
+      const batch = this.pendingItems.splice(0);
+      this.queue.push({
         data: batch,
-        owner: self,
-      }, function(error, result) {
+        owner: this,
+      }, (error, { body }) => {
         if (error) {
-          return self._notify(error, JSON.parse(error.response.body), batch);
+          return this._notify(error, JSON.parse(error.response.body), batch);
         }
-        return self._notify(null, JSON.parse(result.body), batch);
+        return this._notify(null, JSON.parse(body), batch);
       });
     }
   };
 
   // Emit an event when the queue is drained.
-  this.queue.drain = function() {
-    self.emit('drain');
-  };
+  this.queue.drain = () => this.emit('drain')
 };
 util.inherits(ContactImporter, EventEmitter);
 
@@ -71,23 +68,23 @@ ContactImporter.prototype.push = function(data) {
   const batches = chunk(itemsToProcess, this.batchSize);
   debug('generated batches %s from %s items', batches.length, data.length);
 
-  batches.forEach(function(batch) {
+  batches.forEach(batch => {
     // If this batch is full or the queue is empty queue it for processing.
-    if (batch.length === self.batchSize || !self.queue.length()) {
-      self.queue.push({
+    if (batch.length === this.batchSize || !this.queue.length()) {
+      this.queue.push({
         data: batch,
-        owner: self,
-      }, function(error, result) {
+        owner: this,
+      }, function(error, { body }) {
         if (error) {
-          return self._notify(error, JSON.parse(error.response.body), batch);
+          return this._notify(error, JSON.parse(error.response.body), batch);
         }
-        return self._notify(null, JSON.parse(result.body), batch);
+        return this._notify(null, JSON.parse(body), batch);
       });
     }
     // Otherwise, it store it for later.
     else {
       debug('the last batch with only %s item is deferred (partial batch)', batch.length);
-      self.pendingItems = batch;
+      this.pendingItems = batch;
     }
   });
 
@@ -101,14 +98,14 @@ ContactImporter.prototype.push = function(data) {
  * @param {Object} task Task to be processed (data in 'data' property)
  * @param {Function} callback Callback function.
  */
-ContactImporter.prototype._worker = function(task, callback) {
-  const context = task.owner;
-  debug('processing batch (%s items)', task.data.length);
-  context.throttle.submit(context._sendBatch, context, task.data, callback);
+ContactImporter.prototype._worker = function({ owner, data }, callback) {
+  const context = owner;
+  debug(`processing batch (${data.length} items)`);
+  context.throttle.submit(context._sendBatch, context, data, callback);
 };
 
 ContactImporter.prototype._sendBatch = function(context, data, callback) {
-  debug('sending batch (%s items)', data.length);
+  debug(`sending batch (${data.length} items)`);
 
   const request = context.sg.emptyRequest();
   request.method = 'POST';
@@ -116,18 +113,14 @@ ContactImporter.prototype._sendBatch = function(context, data, callback) {
   request.body = data;
 
   context.sg.API(request)
-    .then(function(response) {
+    .then(response => {
       debug('got response: %o', response);
-      setTimeout(function() {
-        context.throttle.incrementReservoir(1);
-      }, context.rateLimitPeriod);
+      setTimeout(() => context.throttle.incrementReservoir(1), context.rateLimitPeriod);
       return callback(null, response);
     })
-    .catch(function(error) {
+    .catch(error => {
       debug('got error, %o', error);
-      setTimeout(function() {
-        context.throttle.incrementReservoir(1);
-      }, context.rateLimitPeriod);
+      setTimeout(() => context.throttle.incrementReservoir(1), context.rateLimitPeriod);
       return callback(error);
     });
 };